FSE Center Fellow David Lobell contributes a commentary to Climate Central on the recent heat wave in Russia, its impact on wheat production and global prices, and what rising temperatures mean in the larger context of climate change and food security.

The heat wave in Russia has captured international media attention, breaking temperature records left and right. It has also captured the attention of commodity traders. You see, in a typical year Russia produces about as much wheat as the United States, and is among the top exporters of wheat flour in the world. But this year, wheat has been decimated in the areas around Moscow, with yield expected to be 30 percent or so below normal. This week Russia announced they are banning all exports of wheat from August 15 through the end of the year. Since late June, wheat prices on the Chicago Board of Trade have risen by 50 percent, to more than $7 a bushel.

It is, and always will be, impossible to say whether a single event is caused by climate change. But we can ask, is this the type of thing we expect to be more common? In terms of warming, we can say with little doubt that heat waves like this will become more common with global warming. Exactly how much more common is tough to say, but it is likely that the average summer in 2050 will be as warm as the warmest summer in the 20th century. I am not aware of anyone who has done the calculation of exactly how common the type of heat experienced this year will be, but based on projections in the UN Intergovernmental Panel on Climate Change (IPCC) reports one can suspect this type of heat wave will be relatively common in Russia in a few decades.

Global meat production has tripled in the past three decades and could double its present level by 2050, according to a new report on the livestock industry by an international team of scientists and policy experts. The impact of this "livestock revolution" is likely to have significant consequences for human health, the environment and the global economy, the authors conclude.

"The livestock industry is massive and growing," said Harold A. Mooney, co-editor of the two-volume report, Livestock in a Changing Landscape (Island Press). Mooney is a professor of biology, senior fellow at the Woods Institute for the Environment and senior fellow at FSI, by courtesy.

"This is the first time that we've looked at the social, economic, health and environmental impacts of livestock in an integrated way and presented solutions for reducing the detrimental effects of the industry and enhancing its positive attributes," he said.

Among the key findings in the report are:

• More than 1.7 billion animals are used in livestock production worldwide and occupy more than one-fourth of the Earth's land.
• Production of animal feed consumes about one-third of total arable land.
• Livestock production accounts for approximately 40 percent of the global agricultural gross domestic product.
• The livestock sector, including feed production and transport, is responsible for about 18 percent of all greenhouse gas emissions worldwide. 

Impacts on humanity

Although about 1 billion poor people worldwide derive at least some part of their livelihood from domesticated animals, the rapid growth of commercialized industrial livestock has reduced employment opportunities for many, according to the report. In developing countries, such as India and China, large-scale industrial production has displaced many small, rural producers, who are under additional pressure from health authorities to meet the food safety standards that a globalized marketplace requires.

Beef, poultry, pork and other meat products provide one-third of humanity's protein intake, but the impact on nutrition across the globe is highly variable, according to the report. "Too much animal-based protein is not good for human diets, while too little is a problem for those on a protein-starved diet, as happens in many developing countries," Mooney noted.

While overconsumption of animal-source foods - particularly meat, milk and eggs - has been linked to heart disease and other chronic conditions, these foods remain a vital source of protein and nutrient nutrition throughout the developing world, the report said. The authors cited a recent study of Kenyan children that found a positive association between meat intake and physical growth, cognitive function and school performance.

Human health also is affected by pathogens and harmful substances transmitted by livestock, the authors said. Emerging diseases, such as highly pathogenic avian influenza, are closely linked to changes in the livestock production but are more difficult to trace and combat in the newly globalized marketplace, they said.

Environmental impacts

The livestock sector is a major environmental polluter, the authors said, noting that much of the world's pastureland has been degraded by grazing or feed production, and that many forests have been clear-cut to make way for additional farmland. Feed production also requires intensive use of water, fertilizer, pesticides and fossil fuels, added co-editor Henning Steinfeld of the United Nations Food and Agriculture Organization (FAO).

Animal waste is another serious concern. "Because only a third of the nutrients fed to animals are absorbed, animal waste is a leading factor in the pollution of land and water resources, as observed in case studies in China, India, the United States and Denmark," the authors wrote. Total phosphorous excretions are estimated to be seven to nine times greater than that of humans, with detrimental effects on the environment.

The beef, pork and poultry industries also emit large amounts of carbon dioxide, methane and other greenhouse gases, Steinfeld said, adding that climate-change issues related to livestock remain largely unaddressed. "Without a change in current practices, the intensive increases in projected livestock production systems will double the current environmental burden and will contribute to large-scale ecosystem degradation unless appropriate measures are taken," he said.

Solutions

The report concludes with a review of various options for introducing more environmentally and socially sustainable practices to animal production systems.

"We want to protect those on the margins who are dependent on a handful of livestock for their livelihood," Mooney said. "On the other side, we want people engaged in the livestock industry to look closely at the report and determine what improvements they can make."

One solution is for countries to adopt policies that provide incentives for better management practices that focus on land conservation and more efficient water and fertilizer use, he said.

But calculating the true cost of meat production is a daunting task, Mooney added. Consider the piece of ham on your breakfast plate, and where it came from before landing on your grocery shelf. First, take into account the amount of land used to rear the pig. Then factor in all the land, water and fertilizer used to grow the grain to feed the pig and the associated pollution that results.

Finally, consider that while the ham may have come from Denmark, where there are twice as many pigs as people, the grain to feed the animal was likely grown in Brazil, where rainforests are constantly being cleared to grow more soybeans, a major source of pig feed.

"So much of the problem comes down to the individual consumer," said co-editor Fritz Schneider of the Swiss College of Agriculture (SHL). "People aren't going to stop eating meat, but I am always hopeful that as people learn more, they do change their behavior. If they are informed that they do have choices to help build a more sustainable and equitable world, they can make better choices."

Livestock in a Changing Landscape is a collaboration of the FAO, SHL, Woods Institute for the Environment, International Livestock Research Institute (ILRI), Scientific Committee for Problems of the Environment (SCOPE), Agricultural Research Center for International Development (CIRAD), and Livestock, Environment and Development Initiative (LEAD).

Other editors of the report are Laurie E. Neville (Stanford University), Pierre Gerber (FAO), Jeroen Dijkman (FAO), Shirley Tarawali (ILRI) and Cees de Haan (World Bank). Initial funding for the project was provided by a 2004 Environmental Venture Projects grant from the Woods Institute.

Editor's Note

To obtain a copy of Livestock in a Changing Landscape, contact Angela Osborn at Island Press: (202) 232-7933 (extension 35) or aosborn@islandpress.org.

In an Op-Ed featured on Huffington Post, aquaculture specialist and FSE director, Rosamond Naylor, supports a newly proposed House bill, the National Sustainable Offshore Aquaculture Act. The bill addresses the potential threats of poorly regulated, intensive fish farming in U.S. ocean waters, and ensures that U.S. aquaculture adopts a science-based, precautionary approach to protect our ocean ecosystems, fishing communities and seafood consumers.

With all eyes on the climate deliberations in Copenhagen, it is more important than ever to find innovative ways of reducing agriculture's contribution to global climate change. The livestock industry in particular has helped feed the world but at a significant cost to the environment, including generating large emissions of greenhouse gas.

One promising solution is to substitute fish production for meat production. But to do so we must ensure that the "blue revolution" in ocean fish farming does not lead to the same suite of environmental problems that have accompanied the "green revolution" for land-based agriculture. Americans' appetite for fish continues to grow and is increasingly met by a year-round supply of fresh fish imported into our marketplace. Yet few Americans know where their fish comes from or how it was produced. Just as most chickens, pigs and cows are raised in tightly confined, intensive operations, so too are many fish.

Right now in the United States we have an opportunity to help ensure that the emerging marine aquaculture sector meets both human and environmental needs. This week, Rep. Lois Capps (D-Calif.) will introduce in the House of Representatives a bill called the National Sustainable Offshore Aquaculture Act that addresses the potential threats of poorly regulated fish farming in U.S. ocean waters. These threats include spread of disease and parasites from farmed to wild fish; discharge of effluents into surrounding waters; misuse of antibiotics and other pharmaceuticals and chemicals; escape of farmed fish into wild fish habitat; killing of marine mammals and sharks that might prey on ocean farm cages; and reliance on use of wild-caught fish in aquaculture feeds, which could deplete food supplies for other marine life and the aquaculture industry itself over time.

These environmental impacts have been evident in many other countries with intensive marine fish farming. The recent collapse of salmon aquaculture in Chile, where industry expansion was prioritized over environmental protection, is the most glaring example. Salmon, one of Chile's leading exports, has suffered a major blow as a result of poor regulation and environmentally unsound management. Tens of thousands of people are now jobless in southern Chile, where the salmon farming industry once boomed.

There are three critical points to be made about the Capps bill. First, unlike previous attempts to legislate on fish farming at the national level, the bill would ensure that U.S. aquaculture adopts a science-based, precautionary approach that establishes a priority for the protection of wild fish and functional ecosystems. This approach is consistent with President Obama's recent call to develop a comprehensive and integrated plan to manage our ocean's many competing uses to ensure protection of vital ecosystem services in years to come.

Second, the Capps bill would preempt the emergence of ecologically risky, piecemeal regulation of ocean fish farming in different regions of the U.S. Efforts are already afoot in Hawaii, California, the Gulf of Mexico and New England to expand marine aquaculture without consistent standards to govern their environmental or social performance. If these piecemeal regional initiatives move forward, there will be little hope of creating a sustainable national policy for U.S. open-ocean aquaculture.

Finally, the Capps bill as currently written has a solid, long-term vision for the appropriate role of fish farming in sustainable ocean ecosystems and thus should win widespread support among environmental and fishing constituencies. It should also garner support from the more progressive end of the aquaculture industry that aspires to sustainable domestic fish production.

Previous federal bills introduced in 2005 and 2007 were fundamentally flawed -- and thus rightly criticized -- because they put the goal of aquaculture expansion far above that of environmental protection. Now, for the first time, a bill has been introduced that would demonstrably protect our ocean ecosystems, fishing communities and seafood consumers from the risks of poorly regulated open-ocean aquaculture.

Rep. Capps and her colleagues are to be commended. Now is the time for the new leadership in Washington -- at the White House and at the National Oceanic and Atmospheric Administration -- to embrace this more science-based and precautionary approach to ensure a sustainable future for U.S. ocean aquaculture.

Berkeley and Stanford - Climate change could increase the likelihood of civil war in sub-Saharan Africa by over 50 percent within the next two decades, according to a new study led by a team of researchers at University of California, Berkeley, Stanford University, New York University and Harvard University, and published in today's (Monday, Nov. 23) online issue of the journal Proceedings of the National Academy of Sciences (PNAS).

The study provides the first quantitative evidence linking climate change and the risk of civil conflict. It concludes by urging accelerated support by African governments and foreign aid donors for new and/or expanded policies to assist with African adaptation to climate change.

"Despite recent high-level statements suggesting that climate change could worsen the risk of civil conflict, until now we had little quantitative evidence linking the two," said Marshall Burke, the study's lead author,  a graduate student at UC Berkeley's Department of Agricultural and Resource Economics, and research associate at the Program on Food Security and the Environment. "Unfortunately, our study finds that climate change could increase the risk of African civil war by over 50 percent in 2030 relative to 1990, with huge potential costs to human livelihoods."

"We were definitely surprised that the linkages between temperature and recent conflict were so strong," said Edward Miguel, professor of economics at UC Berkeley and faculty director of UC Berkeley's Center for Evaluation for Global Action. "But the result makes sense. The large majority of the poor in most African countries depend on agriculture for their livelihoods, and their crops are quite sensitive to small changes in temperature.  So when temperatures rise, the livelihoods of many in Africa suffer greatly, and the disadvantaged become more likely to take up arms."

Understanding the causes and consequences of civil strife in much of the African continent has been a major focus of the social sciences for decades, said Miguel, given the monumental suffering has resulted from it.

In the study, the researchers first combined historical data on civil wars in sub-Saharan Africa with rainfall and temperature records across the continent. They found that between 1980 and 2002, civil wars were significantly more likely in warmer-than-average years, with a 1 degree Celsius increase in temperature in a given year raising the incidence of conflict across the continent by nearly 50 percent.

Building on this historical relationship between temperature and conflict, the researchers then used projections of future temperature and precipitation change to quantify future changes in the likelihood of African civil war. Based on climate projections from 20 global climate models, the researchers found that the incidence of African civil war could increase 55 percent by 2030, resulting in an additional 390,000 battle deaths if future wars are as deadly as recent wars.

All climate models project rising temperatures in coming decades, said David Lobell, study co-author and an assistant professor of environmental earth system science at Stanford and center fellow at Stanford's Program on Food Security and the Environment, a joint program of the Freeman Spogli Institute for International Studies and the Woods Institute for the Environment.

"On average, the models suggest that temperatures over the African continent will increase by a little over 1 degree Celsius by 2030," he added. "Given the strong historical relationship between temperature rise and conflict, this expected future rise in temperature is enough to cause big increases in the likelihood of conflict."

To confirm that this projection was not the result of large effects in just a few countries or due to overreliance on a particular climate model, the researchers recalculated future conflict projections using alternate data.  "No matter what we tried - different historical climate data, different climate model projections, different subsets of the conflict data - we still found the same basic result," said Lobell.

It's easy to think of climate change as a long way off, said the researchers, but their study shows how sensitive many human systems are to small increases in temperature, and how fast the negative impacts of climate change could be felt.

"Our findings provide strong impetus to ramp up investments in African adaptation to climate change, for instance by developing crop varieties less sensitive to extreme heat and promoting insurance plans to help protect farmers from adverse effects of the hotter climate," said Burke.

Applying findings from this study could prove useful to policy makers at the upcoming Copenhagen negotiations in December in determining both the speed and magnitude of response to climate change, the authors said.

"If the sub-Saharan climate continues to warm and little is done to help its countries better adapt to high temperatures, the human costs are likely to be staggering," said Burke.

On September 5th, Ron Raikes was tragically killed in a farm accident. Ron was a stellar Nebraska farmer, an outstanding state senator, a renowned educator, and a good friend of FSE. During the winter quarter of 2008/9, he (and his brother Jeff of the Gates Foundation) spoke to the members of our world food economy class about farming and being a farmer in Nebraska. Ross Feehan was an undergraduate member of that class who went on to become a summer intern on the Raikes farm. Ross’s essay on his experiences is presented here as a tribute to Ron. Roz Naylor Director, FSE

Growing up I always wanted one thing around this time of year: a ride with Santa. Yes, a sky-high journey with that burly, bearded Claus who reportedly could offer children a chance to see the world differently. It seemed like an adventure to me, one that would surely offer a more thorough understanding of Christmas.

As summer recedes and December approaches it appears that my wish was granted this past summer while riding shotgun to and from a farm near the small town of Ashland, Nebraska alongside a man who seemed to a twenty-year-old everything I imagined Santa Claus to be at age seven. For five weeks in the company of a farm operator I had the opportunity to broaden my understanding of commercial food production and the managerial complexity, associated risk, and arrant talent involved in much of agriculture today.

With three separate entities—crop production, cattle feeding, and conservation contracting—the “farm” I traveled to everyday was anything but pedestrian. Most mornings began during the dim hours headed north on a still Route 6, but my early conversations with him were exuberant. In between, and sometimes even during, calls to cattle buyers or astray truckers searching for highways into Ashland free of scales my host would talk to me about cattle market volatility, the method (or madness) ofnegotiation in the feedlot industry, and how trades for heifers and steers from Salina, Kansas hasten grain and livestock futures contracting in Chicago, Illinois. One topic led to the next, and by the time we crossed the railroads at Waverly, we were usually discussing broad issues ranging from the environmental concerns of industrial farming to the social tension in America between people who pejoratively view the actions of Corn Belt farmers and people who produce the food that fills those critics’ plates.

Our driving conversations soon carried over into late mornings and afternoons—anytime when the space for conversation transpired. “The marketplace is fiercely competitive,” he would say to explain the indistinct security governmental support for crop production provides. Daily, his business was subject to environmental and market persuasions. Although federal insurance policies and subsidies were valuable for his business, he was still one of many farmers who jockeyed within a bullish and bearish economy. Prior to hedging his crops, for example, he had to contemplate the eminent yield successes on farms in Iowa in addition to this summer’s drought-induced crop loss in Argentina. But he also could not forget about policy makers in China and Europe who through their governmental measures influence world demand and supply of staple grains. These conversations depicted the realities of an interdependent food market around the globe and helped me distinguish applications of macro-agricultural studies.

Everything I did became part of the learning experience. How could one truly know the size of a bushel of corn without crawling into a storage bin and scooping a truck load into a delivery chute? But before that corn was picked, the farmer had to select a specific variety to be planted from among the many genetically modified products advertised in catalogs and at events similar to a Monsanto luncheon I attended. The “relative maturity” grading system didn’t mean much to me until I ventured out through the warrens of corn and soybean rows to monitor milk lines and black layer emergence in different fields planted with disparate seeds. Working on the farm allowed me to learn hands-on of the agricultural science and technology I had previously studied within classroom walls.

Familiarizing myself with the farm’s operations did not come without mistakes, however. I will never forget the dexterous and visionary employees who taught me not just that wearing shorts while working on a farm is equivalent to modeling a Speedo at a consulting interview, but more importantly how complicated producing food is with advanced mechanized systems. Whether it be welding an auger for grain transfer, converting a piece of scrap metal into a rotating laptop computer harness for the cattle chute, or actually building a propane-powered irrigation pump, the competency of those with whom I worked was remarkable. I learned untold lessons and skills from colleagues, reminding me that a cattle pen could also be an educational setting. 

But no business could be productive without a savvy leader. During my last few weeks in Nebraska I spent time alongside the manager I so esteemed. His ability to synthesize futures and cash market strategies, reconcile input and output data to avert risk, and heed both large issues and small in a multifaceted business was phenomenal. The organization was a machine in itself—protean, even despite its seasonality and daily routine.

I could spend many more months in Ashland refining my tractor driving capabilities and acquiring more knowledge of agricultural management and economics. I wish I could witness the crops reach adulthood and the combines combing those matured fields during the autumn months. Yet, I am grateful for the time I had there, and what I learned will help guide me as I continue to navigate through complex issues facing U.S. agriculture and international food security.

This year I will still anticipate Christmas and its enduring celebrity, but I will rest in bed just a bit more calmly on Santa’s night. My conversations in a Toyota truck this summer and the knowledge gained from the entire experience in Nebraska have sated my sleigh-riding hunger and enhanced my studies of food’s complexities. This farm experience was that kind of ride for me, allowing me to evaluate the impact of U.S. commercial farmers within a global agricultural network, admire those who cultivate what we eat, and seek a deeper understanding of food as a livelihood and resource.

Ever wanted to see the North Pole? Try Nebraska.

Aquaculture, once a fledgling industry, now accounts for 50 percent of the fish consumed globally, according to a new report by an international team of researchers. And while the industry is more efficient than ever, it is also putting a significant strain on marine resources by consuming large amounts of feed made from wild fish harvested from the sea, the authors conclude. Their findings are published in the Sept. 7 online edition of the Proceedings of the National Academy of Sciences (PNAS).

"Aquaculture is set to reach a landmark in 2009, supplying half of the total fish and shellfish for human consumption," the authors wrote. Between 1995 and 2007, global production of farmed fish nearly tripled in volume, in part because of rising consumer demand for long-chain omega-3 fatty acids. Oily fish, such as salmon, are a major source of these omega-3s, which are effective in reducing the risk of cardiovascular disease, according to the National Institutes of Health.

"The huge expansion is being driven by demand," said lead author Rosamond L. Naylor, a professor of environmental Earth system science at Stanford University and director of the Stanford Program on Food Security and the Environment. "As long as we are a health-conscious population trying to get our most healthy oils from fish, we are going to be demanding more of aquaculture and putting a lot of pressure on marine fisheries to meet that need."

Fishmeal and fish oil

To maximize growth and enhance flavor, aquaculture farms use large quantities of fishmeal and fish oil made from less valuable wild-caught species, including anchoveta and sardine. "With the production of farmed fish eclipsing that of wild fish, another major transition is also underway: Aquaculture's share of global fishmeal and fish oil consumption more than doubled over the past decade to 68 percent and 88 percent, respectively," the authors wrote.

In 2006, aquaculture production was 51.7 million metric tons, and about 20 million metric tons of wild fish were harvested for the production of fishmeal. "It can take up to five pounds of wild fish to produce one pound of salmon, and we eat a lot of salmon," said Naylor, the William Wrigley Senior Fellow at Stanford's Woods Institute for the Environment and Freeman Spogli Institute for International Studies.

One way to make salmon farming more environmentally sustainable is to simply lower the amount of fish oil in the salmon's diet. According to the authors, a mere 4 percent reduction in fish oil would significantly reduce the amount of wild-caught fish needed to produce a pound of salmon – from 5 pounds of wild fish to just 3.9 pounds. In contrast, reducing fishmeal use by 4 percent would have very little environmental impact, they said.

"Reducing the amount of fish oil in the salmon's diet definitely gets you a lot more bang for the buck than reducing the amount of fishmeal," Naylor said. "Our thirst for long-chain omega-3 oils will continue to put a lot of strain on marine ecosystems, unless we develop commercially viable alternatives soon."

Naylor and her co-authors pointed to several fish-feed substitutes currently being investigated, including protein made from grain and livestock byproducts, and long-chain omega-3 oils extracted from single-cell microorganisms and genetically modified land plants. "With appropriate economic and regulatory incentives, the transition toward alternative feedstuffs could accelerate, paving the way for a consensus that aquaculture is aiding the ocean, not depleting it," the authors wrote.

Vegetarian fish

Fishmeal and fish oil are important staples at farms that produce carnivorous fish, including salmon, trout and tuna. But vegetarian species, such as Chinese carp and tilapia, can be raised on feed made from plants instead of wild-caught fish. That's one reason why farm-raised vegetarian fish have long been considered environmentally friendly.

In the early 1990s, vegetarian fish farms began adding small amounts of fishmeal in their feed to increase yields. However, between 1995 and 2007, farmers actually reduced the share of fishmeal in carp diets by 50 percent and in tilapia diets by nearly two-thirds, according to the PNAS report. Nevertheless, in 2007, tilapia and carp farms together consumed more than 12 million metric tons of fishmeal – more than 1.5 times the amount used by shrimp and salmon farms combined.

"Our assumption about farmed tilapia and carp being environmentally friendly turns out to be wrong in aggregate, because the sheer volume is driving up the demand," Naylor said. "Even the small amounts of fishmeal used to raise vegetarian fish add up to a lot on a global scale." Removing fishmeal from the diet of tilapia and carp would have a very positive impact on the marine environment, she added.

Regulating fisheries

On the policy front, Naylor pointed to the 2006 California Sustainable Oceans Act and the proposed National Offshore Aquaculture Act, which call for reductions in the use of fishmeal and fish oil in feeds. She also applauded plans by the National Oceanographic and Atmospheric Administration to develop a comprehensive national policy that addresses fisheries management issues posed by aquaculture. "No matter how much is done from the demand side, it is essential that there be regulation on the supply side as well," Naylor said. "You won't prevent the collapse of anchoveta, sardine and other wild fisheries unless those fisheries are carefully regulated."

Other co-authors of the PNAS study are Ronald W. Hardy, University of Idaho; Dominique P. Bureau and Katheline Hua, University of Guelph (Canada); Alice Chiu, Stanford; Matthew Elliott, Sea Change Management; Anthony P. Farrell and Ian Forster, Centre for Aquaculture and Environmental Research (Canada); Delbert M. Gatlin, Texas A&M University and the Norwegian Centres of Excellence; Rebecca J. Goldburg, Pew Charitable Trusts; and Peter D. Nichols, Commonwealth Scientific and Industrial Research Organisation (Australia).

The PNAS report was supported by the David and Lucile Packard Foundation.

Synthetic fertilizers have dramatically increased food production worldwide. But the unintended costs to the environment and human health have been substantial. Nitrogen runoff from farms has contaminated surface and groundwater and helped create massive "dead zones" in coastal areas, such as the Gulf of Mexico. And ammonia from fertilized cropland has become a major source of air pollution, while emissions of nitrous oxide form a potent greenhouse gas.

These and other negative environmental impacts have led some researchers and policymakers to call for reductions in the use of synthetic fertilizers. But in a report published in the June 19 issue of the journal Science, an international team of ecologists and agricultural experts warns against a "one-size-fits-all" approach to managing global food production.

"Most agricultural systems follow a trajectory from too little in the way of added nutrients to too much, and both extremes have substantial human and environmental costs," said lead author Peter Vitousek, a professor of biology at Stanford University and senior fellow at Stanford's Woods Institute for the Environment.

"Some parts of the world, including much of China, use far too much fertilizer," Vitousek said. "But in sub-Saharan Africa, where 250 million people remain chronically malnourished, nitrogen, phosphorus and other nutrient inputs are inadequate to maintain soil fertility."

Other co-authors of the Science report include Woods Institute Senior Fellows Pamela Matson, dean of Stanford's School of Earth Sciences, and Rosamond L. Naylor, director of the Program on Food Security and the Environment.

China and Kenya

In the report, Vitousek and colleagues compared fertilizer use in three corn-growing regions of the world--north China, western Kenya and the upper Midwestern United States.

In China, where fertilizer manufacturing is government subsidized, the average grain yield per acre grew 98 percent between 1977 and 2005, while nitrogen fertilizer use increased a dramatic 271 percent, according to government statistics. "Nutrient additions to many fields [in China] far exceed those in the United States and northern Europe--and much of the excess fertilizer is lost to the environment, degrading both air and water quality," the authors wrote.

Co-author F.S. Zhang of China Agriculture University and colleagues recently conducted a study in two intensive agricultural regions of north China in which fertilizer use is excessive. Their results showed that farmers in north China use about 525 pounds of nitrogen fertilizer per acre (588 kilograms per hectare) annually--releasing about 200 pounds of excess nitrogen per acre (227 kilograms per hectare) into the environment. Zhang and his co-workers also demonstrated that nitrogen fertilizer use could be cut in half without loss of yield or grain quality, in the process reducing nitrogen losses by more than 50 percent.

At the other extreme are the poorer countries of sub-Saharan Africa, such as Kenya and Malawi. In a 2004 study in west Kenya, co-author Pedro Sanchez and colleagues found that farmers used only about 6 pounds of nitrogen fertilizer per acre (7 kilograms per hectare)--little more than 1 percent of the total used by Chinese farmers. And unlike China, cultivated soil in Kenya suffered an annual net loss of 46 pounds of nitrogen per acre (52 kilograms per hectare) removed from the field by harvests.

"Africa is a totally different situation than China," said Sanchez, director of tropical agriculture at the Earth Institute at Columbia University. "Unlike most regions of the world, crop yields have not increased substantially in sub-Saharan Africa. Nitrogen inputs are inadequate to maintain soil fertility and to feed people. So it's not a matter of nutrient pollution but nutrient depletion."

U.S. and Europe

The contrast between Kenya and China is dramatic and will require vastly different solutions, the authors said. However, large-scale change is possible, they said, noting that since the 1980s, increasingly stringent national and European Union regulations and policies have reduced nitrogen surpluses substantially in northern Europe.

In the Midwestern United States, over-fertilization was the norm from the 1970s until the mid-1990s. During that period, tons of excess nitrogen and phosphorus entered the Mississippi River Basin and drained into the Gulf of Mexico, where the large influx of nutrients has triggered huge algal blooms. The decaying algae use up vast quantities of dissolved oxygen, producing a seasonal low-oxygen dead zone in the Gulf that in some years is bigger than the state of Connecticut.

Since 1995, the imbalance of nutrients--particularly phosphorus--has decreased in the Midwestern United States, in part because better farming techniques have increased yields. Statistics show that from 2003 to 2005, annual corn yields in parts of the Midwestern United States and north China were almost the same, even though Chinese farmers used six times more nitrogen fertilizer than their American counterparts and generated nearly 23 times the amount of excess nitrogen.

"U.S. farmers are managing fertilizer more efficiently now," said co-author Rosamond Naylor, who is also a professor of environmental Earth system science and senior fellow at Stanford's Freeman Spogli Institute for International Studies. "The dead zone in the Gulf of Mexico persists due to continued fertilizer runoff and animal waste from increased livestock production."

Low nitrogen in Africa

In sub-Saharan Africa, the initial challenge is to increase productivity and improve soil fertility, the authors said. To meet that challenge, co-author Sanchez recommends that impoverished farmers be given subsidies to purchase fertilizer and good-quality seeds. "In 2005, Malawi was facing a serious food shortage," he recalled. "Then the government began subsidizing fertilizer and corn seeds. In just four years production tripled, and Malawi actually became an exporter of corn."

Food production is paramount, added co-author G. Philip Robertson, a professor of crop and soil sciences at Michigan State University. "Avoiding the misery of hunger is and should be a global human priority," Robertson said. "But we should also find ways to do this without sacrificing other key aspects of human welfare, among them a clean environment. It doesn't have to be an either/or choice."

For countries where over-fertilization is a problem, the authors cited a number of techniques to reduce environmental damage. "Some of these--such as better-targeted timing and placement of nutrient inputs, modifications to livestock diets and the preservation or restoration of riparian vegetation strips--can be implemented now," they wrote.

Designing sustainable solutions also will require a lot more scientific data, they added. "Our lack of effective policies can be attributed, in part, to a lack of good on-farm data about what's happening with nutrient input and loss over time," said co-author Alan Townsend, an associate professor of ecology and evolutionary biology at the University of Colorado-Boulder. "Both China and the European Union have supported agricultural research that yields policy-relevant information on nutrient balances. But the U.S. is particularly lacking in long-term data for a country with such a well-developed scientific enterprise."

Even in Europe, with its strong research programs on nutrient balances and stringent policies for reducing fertilizer runoff, nitrogen pollution remains substantial. "The problem of mitigation of excess nitrogen loss to waters is not easily resolved," said co-author Penny Johnes, director of the Aquatic Environments Research Centre at the University of Reading, U.K. "Society may have to face some difficult decisions about modifying food production practices if real and ecologically significant reductions in nitrogen loss to waters are to be achieved."

According to Vitousek, it is important in the long run to avoid following the same path to excess in sub-Saharan Africa that occurred in the United States, Europe and China. "The past can't be altered, but the future can be and should be," he said. "Agricultural systems are not fated to move from deficit to excess. More effort will be required to develop intensive systems that maintain their yields, while minimizing their environmental footprints."

Other co-authors of the Science report are Tim Crews, Prescott College; Mark David, University of Illinois at Urbana-Champaign; Laurie Drinkwater, Cornell University; Elisabeth Holland, National Center for Atmospheric Research; John Katzenberger, Aspen Global Change Institute; Luiz Martinelli, University of São Paulo, Brazil; Generose Nziguheba, Columbia University; Dennis Ojima, The H. John Heinz III Center for Science, Economics and the Environment; and Cheryl Palm, Columbia University.

This work is based on discussions at the Aspen Global Change Institute supported by NASA, the William and Flora Hewlett Foundation, and the David and Lucile Packard Foundation; and at a meeting of the International Nitrogen Initiative sponsored by the Scientific Committee on Problems of the Environment.